When a great mathematician dies, they often leave plenty of unpublished and incomplete works in their manuscripts. As we assumed that they were a really good mathematician, most of the ideas in these documents could be very interesting and helpful to others in the community even if they are sketchy or incomplete.
Question: What to do in this situation? Is there any legal and copy-right preserving way to publish incomplete ideas, proofs and manuscripts of a dead mathematician? How should this be done? Are there historical examples of such a case?
What I did was post the unpublished stuff on a website; this included collecting copies of some items from some thirty or forty years earlier that had been requested of me. On the other hand, his children (grown) have quite a bit as well.
The most important case of this is Riemann. The collection of papers is usually called by the German word, Nachlass. The reason we have the Riemann Siegel formula is that Siegel was able to go through Riemann's Nachlass. That was in a major university library, probably the best location. More complete story in EDWARDS.